1. Field of the Invention
This invention relates to a projection machine, and more specifically to a projector for generating, annotating, and storing documents, and for interactively communicating the documents and annotations with a remote projector or other electronic device.
2. Description of the Background Art
Document projection devices are well known. The traditional device is a transparency machine consisting of a light box and a beam projection apparatus. The light box contains a projection lamp and a top surface of glass. The transparency is placed upon the glass surface and the lamp shines up through the transparency forming an image beam which is collected, focused, and projected by the beam projection apparatus onto a screen. The beam projection apparatus generally consists of a mirror diagonally positioned between a pair of lenses.
These devices are simple in construction, but offer little flexibility for storing, editing or manipulating the images. In order for the image of a document to be clearly visible on the screen, generally the ambient room light must be reduced. This makes it difficult for viewers in the room to also view other documents or materials while the projected document is being viewed.
Further, no capability exists for communicating these images simultaneously to a remote user, or for a remote user to interactively make changes to the projected image. A number of teleconferencing systems have been designed to enable transmission of images together with audio signals to remote locations. These systems, however, are primarily used for images of different speakers at remote locations, and there are often drawbacks to these systems when used for transmission of images of hard copy documents, partly because of the fine resolution that is often required and also the restrictions on lighting conditions. For example, U.S. Pat. No. 5,369,269, issued to Gotoh et al., discloses a television telephone which performs simultaneous communication of voices and images, and is intended to serve as a multimedia terminal. This device has a camera which is intended for use with images of documents as well as live figures. However the camera and display must be tilted to reduce the effects of external illumination and facilitate viewing of the screen.
What is needed is an apparatus that is designed for projecting documents, which allows the documents to be easily annotated and stored, and which can be simultaneously projected and annotated using a second projector at a remote location. In addition, it is desirable to reduce the unwanted effects of external illumination, to compensate for the effects of lens aberrations, uneven illumination, and various optical reflective properties of different documents, and to provide sufficient resolution to produce readable images of fine print documents.